Police were seen later entering the property and heading to the area where the pallets were discovered.

Officers declined to comment. The FSA confirmed it had seized the meat today.

The new raids came a day after the FSA closed the Peter Boddy Licensed Slaughterhouse in Todmorden, West Yorkshire and Farmbox Meat after an investigation found horses carcasses had been used to make beefburgers and kebabs sold in Britain.

Both companies were raided yesterday by food inspectors and police and full lists of customers were seized.

The raids represent the first time British meat suppliers have been involved in the scandal since contaminated beefburgers were discovered in January.

The FSA said the horse meat passed off as beef was sold in Britain, although it did not know which retailers had stocked it.

Today, Mr Raw-Rees, 64, denied any "knowledge" of the new consignment of meat found behind his property and dismissed suggestions it had been hidden from authorities who raided the plant yesterday.

Mr Raw-Rees, who has operated the plant for the past three years, confirmed the area was his property.

"I have got nothing to hide except, of course, that at the moment the FSA have said some untruths and that is it," he told The Daily Telegraph outside his offices.

"Meat has not been seized. We are working today. It [the allegations] is not true.

"No paperwork has been seized and my plant is in full operation... And we are [de] boning horses. I can't speak OK?"

Told of the pallets of meat that had been found behind his property by The Daily Telegraph and Sky News, he said: "That is news to me."

Asked whether the FSA were "aware" of the pallets yesterday, he replied: "This is something you will have to ask the FSA."

Asked if he had "hidden" the meat before the raids yesterday, he added: "No, no, no", before shutting the door. He also declined to disclose his customers.

Last night he said that until three weeks ago, his plant had specialised in processing beef but that he has recently been contracted to process horse meat sold in Belgium.

He confirmed his plant was visited by police yesterday but denied passing off horse as beef and said he was not supplied by Peter Boddy.

In 2002 he was arrested but not charged for selling illegally slaughtered and unfit meat to the public.

His plant manager Colin Paterson was charged and later cleared of the offence at Swansea Crown Court.

An FSA spokesman confirmed today that more meat had been seized from the property.

He said: "The plant was operating under conditional approval and that has been suspended so they should not be operating.

"It appears that some of the products [from Farmbox Meats] were put on a site next door.

"The meat is now in our custody."

A spokesman for Dyfed Powys police referred inquiries to the FSA.

Previously beefburgers and ready meals contaminated with horse meat have been traced to Romania and Poland.

The FSA has said that the Peter Boddy Licenced Slaughterhouse had supplied Farmbox Meats, with horse carcasses.

Owen Patterson, the Environment Secretary, said it was “absolutely shocking” that British slaughterhouses have now been linked to the scandal.

"It is totally unacceptable if any business in the UK is defrauding the public by passing off horse meat as beef," he said last night.

"I expect the full force of the law to be brought down on anyone involved in this kind of activity."

Mr Boddy, 63, runs a slaughterhouse from his farm, which is licensed to kill cattle, horses, poultry and even ostriches. He also runs a separate business which specialises in capturing dangerous and wild animals, including horses which have bolted.

His website states: “Peter has been involved in the live animal capture business for over 20 years and is recognized as one of the most highly spoken specialists in a very demanding line of work.”

He also rears red stags for breeding at a deer park. The Daily Telegraph on Tuesday spoke to Mr Boddy’s son, who declined to be named but said: “It’s a load of hype, it’s not true. It’s crap.”

It is understood the meat, some of which was open to the elements, had been sitting behind the industrial estate-based plant since about 2pm yesterday.

Sources close to the company insisted they had been able to "process" meat but were not allowed to ship products to and from the factory.

It remains unclear this afternoon whether production had been fully suspended.